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Message-ID: <871pyzz9i0.wl-tiwai@suse.de>
Date: Mon, 25 Nov 2024 15:13:59 +0100
From: Takashi Iwai <tiwai@...e.de>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: Takashi Iwai <tiwai@...e.de>,
syzbot <syzbot+351f8764833934c68836@...kaller.appspotmail.com>,
linux-kernel@...r.kernel.org,
linux-sound@...r.kernel.org,
perex@...ex.cz,
syzkaller-bugs@...glegroups.com,
tiwai@...e.com
Subject: Re: [syzbot] [sound?] BUG: sleeping function called from invalid context in vfree
On Mon, 25 Nov 2024 15:07:50 +0100,
Eric Dumazet wrote:
>
>
> On 11/25/24 2:34 PM, Takashi Iwai wrote:
> > On Mon, 25 Nov 2024 13:58:09 +0100,
> > Eric Dumazet wrote:
> >>
> >> On 11/25/24 1:54 PM, syzbot wrote:
> >>> Hello,
> >>>
> >>> syzbot found the following issue on:
> >>>
> >>> HEAD commit: 9f16d5e6f220 Merge tag 'for-linus' of git://git.kernel.org..
> >>> git tree: upstream
> >>> console output: https://syzkaller.appspot.com/x/log.txt?x=154bc778580000
> >>> kernel config: https://syzkaller.appspot.com/x/.config?x=47cc5fc1922531f
> >>> dashboard link: https://syzkaller.appspot.com/bug?extid=351f8764833934c68836
> >>> compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> >>> userspace arch: i386
> >>>
> >>> Unfortunately, I don't have any reproducer for this issue yet.
> >>>
> >>> Downloadable assets:
> >>> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-9f16d5e6.raw.xz
> >>> vmlinux: https://storage.googleapis.com/syzbot-assets/dddd5525a287/vmlinux-9f16d5e6.xz
> >>> kernel image: https://storage.googleapis.com/syzbot-assets/7c9e082ba50b/bzImage-9f16d5e6.xz
> >>>
> >>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> >>> Reported-by: syzbot+351f8764833934c68836@...kaller.appspotmail.com
> >>>
> >>> BUG: sleeping function called from invalid context at mm/vmalloc.c:3359
> >>> in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 6938, name: syz.1.230
> >>> preempt_count: 1, expected: 0
> >>> RCU nest depth: 0, expected: 0
> >>> 2 locks held by syz.1.230/6938:
> >>> #0: ffff88804a2d2968 (&rmidi->open_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:201 [inline]
> >>> #0: ffff88804a2d2968 (&rmidi->open_mutex){+.+.}-{4:4}, at: snd_rawmidi_output_params+0x51/0x1c0 sound/core/rawmidi.c:748
> >>> #1: ffff888045e5ed48 (&substream->lock){....}-{3:3}, at: spin_lock_irq include/linux/spinlock.h:376 [inline]
> >>> #1: ffff888045e5ed48 (&substream->lock){....}-{3:3}, at: class_spinlock_irq_constructor include/linux/spinlock.h:565 [inline]
> >>> #1: ffff888045e5ed48 (&substream->lock){....}-{3:3}, at: resize_runtime_buffer+0x243/0x530 sound/core/rawmidi.c:727
> >>> irq event stamp: 1218
> >>> hardirqs last enabled at (1217): [<ffffffff8b189e32>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
> >>> hardirqs last enabled at (1217): [<ffffffff8b189e32>] _raw_spin_unlock_irqrestore+0x52/0x80 kernel/locking/spinlock.c:194
> >>> hardirqs last disabled at (1218): [<ffffffff8b189ad5>] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:117 [inline]
> >>> hardirqs last disabled at (1218): [<ffffffff8b189ad5>] _raw_spin_lock_irq+0x45/0x50 kernel/locking/spinlock.c:170
> >>> softirqs last enabled at (0): [<ffffffff814e57ac>] copy_process+0x1e9c/0x6f20 kernel/fork.c:2321
> >>> softirqs last disabled at (0): [<0000000000000000>] 0x0
> >>> Preemption disabled at:
> >>> [<0000000000000000>] 0x0
> >>> CPU: 1 UID: 0 PID: 6938 Comm: syz.1.230 Not tainted 6.12.0-syzkaller-09073-g9f16d5e6f220 #0
> >>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> >>> Call Trace:
> >>> <TASK>
> >>> __dump_stack lib/dump_stack.c:94 [inline]
> >>> dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
> >>> __might_resched+0x3c0/0x5e0 kernel/sched/core.c:8758
> >>> vfree+0x75/0x890 mm/vmalloc.c:3359
> >>> kvfree+0x33/0x50 mm/util.c:699
> >>> resize_runtime_buffer+0x3a7/0x530 sound/core/rawmidi.c:736
> >>> snd_rawmidi_output_params+0xeb/0x1c0 sound/core/rawmidi.c:751
> >>> snd_rawmidi_ioctl_params_compat sound/core/rawmidi_compat.c:37 [inline]
> >>> snd_rawmidi_ioctl_compat+0x3ac/0x3e0 sound/core/rawmidi_compat.c:120
> >>> __do_compat_sys_ioctl+0x1cb/0x2c0 fs/ioctl.c:1004
> >>> do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
> >>> __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
> >>> do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
> >>> entry_SYSENTER_compat_after_hwframe+0x84/0x8e
> >>> RIP: 0023:0xf7f01579
> >>> Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
> >>> RSP: 002b:00000000f506555c EFLAGS: 00000296 ORIG_RAX: 0000000000000036
> >>> RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 00000000c0205710
> >>> RDX: 0000000020000100 RSI: 0000000000000000 RDI: 0000000000000000
> >>> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> >>> R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
> >>> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> >>> </TASK>
> >>> ----------------
> >>> Code disassembly (best guess), 2 bytes skipped:
> >>> 0: 10 06 adc %al,(%rsi)
> >>> 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi
> >>> 6: 10 07 adc %al,(%rdi)
> >>> 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi
> >>> c: 10 08 adc %cl,(%rax)
> >>> e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi
> >>> 1e: 00 51 52 add %dl,0x52(%rcx)
> >>> 21: 55 push %rbp
> >>> 22: 89 e5 mov %esp,%ebp
> >>> 24: 0f 34 sysenter
> >>> 26: cd 80 int $0x80
> >>> * 28: 5d pop %rbp <-- trapping instruction
> >>> 29: 5a pop %rdx
> >>> 2a: 59 pop %rcx
> >>> 2b: c3 ret
> >>> 2c: 90 nop
> >>> 2d: 90 nop
> >>> 2e: 90 nop
> >>> 2f: 90 nop
> >>> 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
> >>> 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
> >>>
> >>>
> >>> ---
> >>> This report is generated by a bot. It may contain errors.
> >>> See https://goo.gl/tpsmEJ for more information about syzbot.
> >>> syzbot engineers can be reached at syzkaller@...glegroups.com.
> >>>
> >>> syzbot will keep track of this issue. See:
> >>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> >>>
> >>> If the report is already addressed, let syzbot know by replying with:
> >>> #syz fix: exact-commit-title
> >>>
> >>> If you want to overwrite report's subsystems, reply with:
> >>> #syz set subsystems: new-subsystem
> >>> (See the list of subsystem names on the web dashboard)
> >>>
> >>> If the report is a duplicate of another one, reply with:
> >>> #syz dup: exact-subject-of-another-report
> >>>
> >>> If you want to undo deduplication, reply with:
> >>> #syz undup
> >>
> >> Bug added in
> >>
> >> commit 84bb065b316e8367e14a8824a8f4d21056b10c53
> >> Author: Takashi Iwai <tiwai@...e.de>
> >> Date: Tue Feb 27 09:52:51 2024 +0100
> >>
> >> ALSA: rawmidi: Use guard() for locking
> >>
> >> We can simplify the code gracefully with new guard() macro and co for
> >> automatic cleanup of locks.
> >>
> >> There are a few remaining explicit mutex and spinlock calls, and those
> >> are the places where the temporary unlock/relocking happens -- which
> >> guard() doens't cover well yet.
> >>
> >> Only the code refactoring, and no functional changes.
> >>
> >> Signed-off-by: Takashi Iwai <tiwai@...e.de>
> >> Link:https://lore.kernel.org/r/20240227085306.9764-10-tiwai@suse.de
> >> <https://lore.kernel.org/r/20240227085306.9764-10-tiwai@suse.de>
> > Hmm, through a quick glance, I don't see anything breaking there.
> >
> > Could you tell me which code path introduced the spinlock held during
> > kvzalloc() call in resize_runtime_buffer() in sound/core/rawmidi.c by
> > this commit...?
>
>
> @@ -744,9 +724,8 @@ static int resize_runtime_buffer(struct
> snd_rawmidi_substream *substream,
> newbuf = kvzalloc(params->buffer_size, GFP_KERNEL);
> if (!newbuf)
> return -ENOMEM;
> - spin_lock_irq(&substream->lock);
> + guard(spinlock_irq)(&substream->lock);
> if (runtime->buffer_ref) {
> - spin_unlock_irq(&substream->lock);
> kvfree(newbuf);
> return -EBUSY;
> }
> @@ -754,7 +733,6 @@ static int resize_runtime_buffer(struct
> snd_rawmidi_substream *substream,
> runtime->buffer = newbuf;
> runtime->buffer_size = params->buffer_size;
> __reset_runtime_ptrs(runtime, is_input);
> - spin_unlock_irq(&substream->lock);
> kvfree(oldbuf);
> }
> runtime->avail_min = params->avail_min;
>
>
> You can see that after your patch, kvfree() is called while
>
> guard(spinlock_irq)(&substream->lock); is still holding the lock.
Ah, thanks, it's it's kvfree() call, not kvzalloc().
Will submit the fix patch soon later.
Takashi
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